a lot of people here seek a volume rate of about 10 x tanks I pr. hour too achieve optimal bacteriological filtration and add a circulation pump for flow. I actually have a very small internal and only tweaked co2 flow for better result. So if money is an issue then I think I would start with a small circulation pump like a korelia. If money isn't an issue I'd go for both. Try posting your search for both in the proper section since it's been a long time since I had a big tank so I'm not up to date on brands and quality. I used to be an Eheim fan but something better and cheaper might be available now.
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Bit of progress looking a lot better than it did!
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